A test that reproduces a bug which is reported in the #551 issue

Author: plokhotnyuk

jsoniter-scala-macros/shared/src/test/scala/com/github/plokhotnyuk/jsoniter_scala/macros/JsonCodecMakerSpec.scala

@@ -1878,16 +1878,18 @@ class JsonCodecMakerSpec extends VerifyingSpec {
 
       sealed trait GADT2[A] extends Product with Serializable
 
-      case class IsDir(path: String) extends GADT2[_root_.scala.Boolean]
+      object GADT2 {
+        case class IsDir(path: String) extends GADT2[_root_.scala.Boolean]
 
-      case class Exists(path: String) extends GADT2[_root_.scala.Boolean]
+        case class Exists(path: String) extends GADT2[_root_.scala.Boolean]
 
-      case class ReadBytes(path: String) extends GADT2[_root_.scala.Array[_root_.scala.Byte]]
+        case class ReadBytes(path: String) extends GADT2[_root_.scala.Array[_root_.scala.Byte]]
 
-      case class CopyOver(src: Seq[_root_.scala.Byte], path: String) extends GADT2[Int]
+        case class CopyOver(src: Seq[_root_.scala.Byte], path: String) extends GADT2[Int]
+      }
 
       verifySerDeser(make[Array[GADT2[_]]],
-        _root_.scala.Array[GADT2[_]](Exists("WWW"), ReadBytes("QQQ"), CopyOver("AAA".getBytes.toSeq, "OOO")),
+        _root_.scala.Array[GADT2[_]](GADT2.Exists("WWW"), GADT2.ReadBytes("QQQ"), GADT2.CopyOver("AAA".getBytes.toSeq, "OOO")),
         """[{"type":"Exists","path":"WWW"},{"type":"ReadBytes","path":"QQQ"},{"type":"CopyOver","src":[65,65,65],"path":"OOO"}]""")
     }
     "serialize and deserialize higher-kinded types" in {